Kev Tshawb Fawb

Kev Nkag Siab
Ib lub cev khov kho suav tias yog muaj ntau yam khoom me me, thiab qhov hnyav ntawm ib yam khoom yog qhov sib sau ua ke ntawm cov khoom me me uas ua rau yam khoom ntawd. Qhov chaw nruab nrab ntawm qhov hnyav yog ib qho chaw ntawm ib yam khoom uas qhov hnyav ntawm txhua yam khoom me me uas ua rau yam khoom ntawd suav tias yog sib sau ua ke ntawm qhov ntawd.

Cov mis
Txhua lub cev khov kho raug xav tias muaj ntau yam khoom me me, txhua yam sib nrug sib luag. Txawm li cas los xij, txhawm rau kom yooj yim rau kev txiav txim siab qhov chaw nruab nrab ntawm pawg, kev yooj yim yog ua los ntawm kev xav tias lub cev khov kho tsuas muaj ob lub khoom me me xwb. Ob lub khoom me me no tuaj yeem hu ua lub cev khov kho.

nyeem ntxiv

Kawm txog Cov Lus Nug Piv Txwv ntawm Center of Gravity

Nkag Siab Txog Qhov Chaw Ntawm Lub ntiajteb txawj nqus
Ib yam khoom khov kho raug suav hais tias yog tsim los ntawm ntau yam khoom me me vim qhov no lub zog gravitational ua haujlwm rau txhua yam ntawm cov khoom me me no. Hauv lwm lo lus, txhua yam khoom me me muaj nws qhov hnyav. Lub hauv paus ntawm lub ntiajteb txawj nqus ntawm ib yam khoom yog ib qho chaw nyob rau ntawm lossis ze ntawm yam khoom uas qhov hnyav ntawm txhua qhov ntawm yam khoom tau sib sau ua ke.

Yog tias ib yam khoom zoo ib yam (qhov ceev ntawm qee yam khoom zoo ib yam lossis yam khoom muaj cov khoom zoo sib xws) thiab cov duab ntawm yam khoom yog sib npaug (piv txwv li plaub fab, plaub fab plaub fab, lub voj voog) ces qhov chaw nruab nrab ntawm lub ntiajteb txawj nqus ntawm yam khoom sib phim nrog qhov chaw nruab nrab ntawm qhov hnyav ntawm yam khoom uas nyob hauv nruab nrab ntawm yam khoom. Rau ib daim duab peb ceg, qhov chaw nruab nrab ntawm qhov hnyav nyob ntawm 1/3 h, qhov twg h = qhov siab ntawm daim duab peb ceg.

nyeem ntxiv

Tsis yog txhua yam khoom uas peb ntsib hauv lub neej txhua hnub yeej ib txwm so. Ib yam khoom yuav so thaum xub thawj, tab sis yog tias nws raug txav mus los, nws tuaj yeem txav mus los. Lo lus nug yog seb nws puas rov qab mus rau nws qhov chaw qub tom qab txav mus los. Qhov no nyob ntawm qhov kev txav mus los. hom kev sib npaug ntawm cov khoom tus.
Yog tias ib yam khoom uas so tsis txav muaj kev cuam tshuam (muaj lub zog tshwm sim los yog lub sijhawm ntawm lub zog ua rau yam khoom) ces yam khoom ntawd yuav txav mus. Tom qab txav mus, yuav muaj peb txoj hauv kev, uas yog: (1) yam khoom rov qab mus rau nws qhov chaw qub, (2) yam khoom txav tawm ntawm nws qhov chaw qub, (3) yam khoom tseem nyob hauv nws qhov chaw tshiab. Yog tias tom qab txav mus, yam khoom rov qab mus rau nws qhov chaw qub ces yam khoom ntawd nyob hauv ruaj khov sib npaugYog tias tom qab txav mus lawm, qhov khoom txav mus deb ntawm nws qhov chaw qub, ces qhov khoom ntawd nyob hauv tsis ruaj khovNtawm qhov tod tes, yog tias tom qab txav mus rau qhov khoom tseem nyob hauv nws qhov chaw tshiab, ces qhov khoom ntawd nyob hauv qhov sib npaug nruab nrab.

nyeem ntxiv

2 Piv txwv ntawm cov lus nug txog kev sib npaug ntawm cov khoom me me

1. Muab ib yam khoom uas hnyav 10 kg dai rau ntawm ib txoj hlua. Xam seb txoj hlua ntawd muaj zog npaum li cas (T)! g = 10 m/s²
Kev Sib Tham

nyeem ntxiv

5 Piv txwv ntawm lub zog kinetic thiab cov lus nug txog kev ua haujlwm physics

1. Lub tsheb uas hnyav 5000 kg thaum xub thawj nres, thiab tom qab ntawd txav mus rau qhov ceev ntawm 20 m/s. Txheeb xyuas tag nrho cov haujlwm ua tiav rau lub tsheb...
Kev Sib Tham
Nws yog paub :
Qhov hnyav (m) = 5000 kg
Qhov ceev pib (v_o) = 0 m/s (thawj zaug lub tsheb nres twj ywm)
Qhov ceev kawg (v_t) = 20 m/s
Nug Tag nrho cov kev siv zog

nyeem ntxiv

15 Piv txwv ntawm Cov Lus Nug Txog Lub Ntsiab Cai ntawm Dub

1. Cov dej khov uas muaj qhov hnyav li 0,2 kg raug sib xyaw nrog cov tshuaj yej sov uas muaj qhov hnyav li 0,2 kg. Qhov kub ntawm cov dej khov = - 10 ^o C, qhov kub ntawm cov tshuaj yej sov = 40 ^o C. Qhov kub tshwj xeeb ntawm cov dej khov = 2100 J/kg C ^o , qhov kub tshwj xeeb ntawm dej = 4200 J/kg C ^o , qhov kub ntawm kev sib xyaw ntawm dej = 334.000 J/kg. Yog tias cov dej khov thiab cov tshuaj yej sov raug sib xyaw ua ke hauv ib lub kaw lus kaw, txiav txim siab qhov kub kawg ntawm qhov sib tov.

Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm dej khov (m es) = 0,2 kg
Qhov hnyav ntawm dej tshuaj yej sov (m tshuaj yej) = 0,2 kg
Cov cua sov tshwj xeeb ntawm dej (c dej) = 4180 J/kg C^o
Qhov kub tshwj xeeb ntawm dej khov (c es) = 2100 J/kg C^o
Kub ntawm kev sib xyaw ntawm dej (L)_f dej) = 334.000 J/kg

nyeem ntxiv

5 piv txwv ntawm kev hloov pauv ntawm lub kaum sab xis thiab kev hloov pauv ntawm txoj kab ncaj nraim hauv kev txav mus los

1. Ib lub log uas muaj lub vojvoog ntawm 30 cm tig ib qho deb ntawm 10 radians. Ib qho ntawm ntug ntawm lub log mus deb npaum li cas?
Kev Sib Tham
Qhov deb ntawm ntug ntawm lub log thiab nruab nrab ntawm lub log = lub vojvoog ntawm lub log.
Nws paub tias:
Lub vojvoog (r) = 30 cm = 0,3 meters
Ces kaum (tus phauj) = 10 radians
Nug: qhov deb uas tau mus ncig (s)
Lus teb:

nyeem ntxiv

2 Piv txwv ntawm cov lus nug txog kev txiav txim siab qhov vector tshwm sim siv cov vectors sib xyaw

1. F ₁ = 6 N, F ₂ = 10 N. Qhov tshwm sim ntawm ob lub zog vectors yog…

Kev Sib Tham
F_1x =F₁ coj 60^o = (6)(0,5) = 3 N (zoo vim nws nyob rau hauv qhov kev taw qhia x zoo)
F_2x =F₂ coj 30^o = (10)(0,5√3) = 5√3 = (5)(1,372) = -8,66 N (tsis zoo vim nws nyob rau hauv qhov kev taw qhia x tsis zoo)
F_1y =F₁ kev txhaum 60^o = (6)(0,5√3) = 3√3 = (3)(1,372) = 4,116 N (zoo vim nws nyob rau hauv qhov kev taw qhia y zoo)
F_2y =F₂ kev txhaum 30^o = (10)(0,5) = -5 N (tsis zoo vim nws nyob rau hauv qhov kev taw qhia y tsis zoo)

nyeem ntxiv

2 Piv txwv ntawm cov lus nug txog kev txiav txim siab cov khoom vector

1. Lub zog vector F = 20 Newton tsim lub kaum sab xis ntawm 30 ^o rau qhov x-axis zoo. Txheeb xyuas cov khoom ntawm vector F ntawm x-axis (F _x ) thiab y-axis (F _y ).

Kev Sib Tham
F_x = F cos 30^o = (20)(cos 30^o) = (20)(0,5√3) = 10√3 Newtons

nyeem ntxiv

Kawm cov piv txwv ntawm cov teeb meem ntawm kev cuam tshuam thiab kev diffraction ntawm lub teeb - ib qho slit , tom qab ntawd ua haujlwm rau cov teeb meem ntawm kev cuam tshuam thiab kev diffraction ntawm lub teeb.

1. Lub teeb uas muaj qhov ntev ntawm 700 nm hla dhau ib qho qhov uas muaj qhov dav ntawm 0,2 hli. Tus qauv diffraction ntawm lub vijtsam yog nyob ntawm qhov deb ntawm 50 cm ntawm qhov qhov. Txheeb xyuas qhov deb ntawm kab tsaus thib ob thiab kab teeb loj.
Kev Sib Tham

nyeem ntxiv